One of the first things you get told as a writer is “write what you know”.

Which is a fine idea, out of which you will probably get precisely one book.

First novels are wonderful things, into which we pour everything, all our heartbreak and joy and love and hate and intimate knowledge of the internal combustion engine and the 1969 Football Association Challenge Cup Final.

They can be a cathartic experience. Sometimes they can actually be good novels. And on occasion, they can actually be published. But they’re a necessary step on the road to becoming a novelist, and once they’re done they free up the writer to do the stuff that’s really fun about writing books, and which no-one really tells you about.

I’m talking about writing what you don’t know.

The third book in my Gideon Smith series of alternate-history Victorian fantasies (oh, go on, then, call it steampunk if you want to – I’m feeling in expansive mood) is published today, via Tor in the US and Snowbooks in the UK. It’s called Gideon Smith and the Mask of the Ripper and it’s absolutely stuffed to the gunwales with things I don’t know – or at least, I didn’t know before I started writing it.

If there’s one big idea in Mask of the Ripper, I suppose it would be identity, and whether we really are what we think ourselves to be and what other people tell us we should or shouldn’t be. This is explored in various ways – the (nominal) protagonist Gideon is stripped of his memory and set adrift in a riot-torn London of Christmas 1890; a major character is charged with murder and their identity which we have come to accept is revealed to be a carefully constructed fiction. Then there is Maria, the mechanical girl introduced in the first book, who is seeking some answers concerning her own place in the world.

But dancing around the big idea are lots and lots of little ideas, and these zephyrs which keep the main theme aloft are largely composed of things of which I knew nothing before writing the book, or at least knew very little.

It can be quite exciting. It’s pointing your airship at the bit of the map marked terra incognita, here be dragons, do not cross. It’s stretching your writerly muscles, rather than just chucking in the same old same old.

Thus, for Mask of the Ripper, I found myself learning all about the early days of research into DNA. It was quite important for me that the trial of the character on a murder charge featured this timeline’s first usage in criminal proceedings of DNA evidence. Only problem was, 1890 was a little early for this in reality.

So I had to find out when it all happened, fit it into my own alternate-history, and spend long hours chewing over often impenetrable essays so I could work out whether or not I could have what I wanted: a device or machine that would allow DNA samples to be tested in front of a Crown Court jury with rather dramatic results.

(The scientists among you will be throwing up their hands in horror; relax. This is fantasy. I got all of the science together, gave it a bit of a stir, then made some stuff up. It happens).

For another character, I needed some motivation that would put him in London’s sewers with a team of Thuggee assassins. I came up with the Great Famine of 1876-78 in India. The sub-continent at that time was, of course, under the control of the British Empire, both in reality and in Gideon Smith’s world. The British were building a great canal, a show of strength, a Victorian architectural and engineering marvel – but ultimately a folly. Hundreds of thousands of Indians died in the famine, and the British made it worse by putting them to work on the canal that would ultimately carry their rice and grain away from the starving masses and on to British dinner tables. So, yeah, motivation there.

And finally, I had Gloria Monday. Gloria is just a supporting character in the book, and I wish I could have made more of her. Gloria is a trans woman, another concept I had to bend to my steampunk will to make it fit into my timeline. I’m indebted to Cheryl Morgan, a writer an publisher who looked at my Gloria chapters and deemed them to be, if not wonderful, at least not as offensive as they could be.

Because as a white dude from the north of England, the chances are I’m going to have screwed that one up substantially. And fear of that almost made me not write Gloria.

But… write what you don’t know.

Why? Well, a writer who repeatedly dashes off novels that require no research or stretching of imagination and knowledge would, eventually, be doing their readers a disservice, I think.

Certainly, I would. If I wrote only what I know, or was comfortable with writing, it would make for very boring books in the long run, safe books, books that take no chances.

There’s always a risk with taking chances that you will offend, upset, just plain get it all wrong wrong wrong and piss everyone off.

Or you may get it completely right and be the toast of book-land.

Or, which is more likely, you may get it both right and wrong, but with a bit of a tailwind you might get it more right than wrong, have learned something in the process, and planted your flag in a tiny little bit of terra incognita… at least for you.

I actually purchased the first two Gideon Smith books but for some reason have never gotten around to reading them. Too many books, too little time. You have reminded me that I must rectify this situation immediately. Gideon Smith is clawing his way to the top of Mt TBR as we speak.